I have made a simple model in BEopt of a single story 2000-sqft house with no basement which I am testing for three locations in Texas. In one design case I increase efficiency of central AC from SEER13 to SEER 18. Sure enough, my site energy use for cooling reduces from 13.6 to 10.1 MMBtu, but my site energy use for heating has increased from 27.2 to 31.4 MMBtu. This is for Austin Texas. I made no other changes to the design other than the AC efficiency. Is the extra heating energy due to reheat of conditioned air? Or could there be some other dynamics in BEopt which could produce this result.
Thanks in advance.
Peter
